I have 1 gig in my imac. Can I still download and use Lion, or do I have to have 2 gigs to run it?

I have IOS 10.6.8 right now. 2GHz Intel Core 2 Duo processor, 1 GB 667 MHz DDR2 SDRAM, startup disc Macintosh HD, Model identifier iMac7,1. I have 2 cores, 1 GB of memory, Bus Speed 800 MHz. Can I go straight to Mountain Lion, or do I have to get Lion first, and will it run on my computer?